The polyamide resin has excellent mechanical properties, heat resistance and chemical resistance and is preferably used in the application of automobiles and electric and electronic components. For example, the polyamide resin is preferably used for under-hood components of automobiles and sliding components such as gears of automobiles and electric and electronic components. As a recent trend, however, better heat aging resistance and chemical resistance are needed for the under-hood components, and better abrasion resistance and fatigue resistance are needed for the sliding components. With the growing demand for downsizing and wall thinning of molded products, a high level of flowability is also needed during molding. There is accordingly a demand for a resin material having such properties in combination.
For example, a polyamide resin composition including a polyamide resin and a polyol having a melting point of 150 to 280° C. has been proposed as the technique of improving the flowability of the polyamide resin composition (see, for example, EP 1041109A). In another example, polyamide resin compositions including a polyamide resin, a polyol having a number-average molecular weight of less than 2,000, an auxiliary stabilizer such as a copper stabilizer and a polymer reinforcing agent have been proposed as the technique of improving the heat aging resistance (see, for example, US 2010/0028580A and US 2010/0029819A). A water-absorbing cellulose resin using, for example, a polyvalent glucose carboxylate having a hydroxyl group and a carboxyl group has been proposed, on the other hand, as the technique of improving the mechanical strength and the moisture resistance (see, for example, JP H10-204101A).
The above polyamide resin compositions described in US 2010/0028580A and US 2010/0029819A, however, have insufficient heat aging resistance in a temperature range of lower than 150° C., although having a high heat aging resistance in a temperature range of 150° C. to 230° C. The above polyamide resin compositions described in US 2010/0028580A and US 2010/0029819A accordingly have room for improvement in heat aging resistance. The above polyamide resin compositions described in US 2010/0028580A and US 2010/0029819A also have a problem with surface appearance, for example, bleeding out the polyol to the surface layer of the molded product and have insufficient abrasion resistance, fatigue resistance and chemical resistance. The resin compositions described in EP 1041109A and JP H10-204101A have insufficient abrasion resistance, fatigue resistance, chemical resistance and surface appearance. By taking into account these problems, it could be helpful to provide a polyamide resin composition used to produce a molded product having excellent abrasion resistance, fatigue resistance, heat aging resistance, chemical resistance and surface appearance.